Process for the catalytic synthesis of biaryls and polymers from aryl compounds

ABSTRACT

A process for producing organic substituted aromatic or heteroaromatic compounds including biaryl and biheteroaryl compounds in a two-step reaction. In the first step, the aromatic or heteroaromatic compound is borylated in a reaction comprising a borane or diborane reagent (any boron reagent where the boron reagent contains a B—H, B—B or B—Si bond) and an iridium or rhodium catalytic complex. In the second step, a metal catalyst catalyzes the formation of the organic substituted aromatic or heteroaromatic compound from the borylated compound and an electrophile such as an aryl or organic halide, triflate (OSO 2 CF 3 ), or nonaflate (OSO 2 C 4 F 9 ). The steps in the process can be performed in a single reaction vessel or in separate reaction vessels. The present invention also provides a process for synthesis of complex polyphenylenes starting from halogenated aromatic compounds.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to Provisional Application No.60/305,107, filed Jul. 13, 2001, and to Provisional Application No.60/332,092, filed Nov. 21, 2001.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

This invention was supported in part by National Institutes of Health,National Institute of General Medical Sciences Grant No. R01 GM63188-01and in part by National Science Foundation Grant No. CHE-9817230. TheU.S. government has certain rights in this invention.

REFERENCE TO A “COMPUTER LISTING APPENDIX SUBMITTED ON A COMPACT DISC”

Not Applicable.

BACKGROUND OF THE INVENTION

(1) Field of the Invention

The present invention relates to a process for producing organicsubstituted aromatic or heteroaromatic compounds including biaryl andbiheteroaryl compounds in a two-step reaction. In the first step, thearomatic or heteroaromatic compound is borylated in a reactioncomprising a borane or diborane reagent (any boron reagent where theboron reagent contains a B—H, B—B or B—Si bond) and an iridium orrhodium catalytic complex. In the second step, a metal catalystcatalyzes the formation of the organic substituted aromatic orheteroaromatic compound from the borylated compound and an electrophilesuch as an organic or aryl halide, triflate (OSO₂CF₃), or nonaflate(OSO₂C₄F₉). The steps in the process can be performed in a singlereaction vessel or in separate reaction vessels. The present inventionalso provides a process for synthesis of complex polyphenylenes startingfrom halogenated aromatic compounds.

(2) Description of Related Art

Carbon-carbon bonds are the molecular “bricks and mortar” from whichdiverse architectures in living organisms and man-made materials areconstructed. As the field of organic chemistry has evolved, numerousmethods for carbon-carbon bond construction have been developed, rangingfrom classic examples, like the Diels-Alder reaction, to more recentmetal-catalyzed processes such as olefin polymerizations and metatheses.

Substituted aromatic, and their heteroaromatic analogs, are abundant innatural and in synthetic materials. Consequently, controlled methods forlinking aromatic rings via C—C sigma bonds have long been pursued byorganic chemists. Activity in this regard intensified in the late 1970'sduring which Pd catalyzed methods for C—C bond construction emerged(Diederich and Stang, Metal-Catalyzed Cross-Coupling Reactions.Wiley-VCH, New York (1998)). Notably, the Pd catalyzed coupling of anarylboronic acid and an aryl halide disclosed by Miyaura and Suzuki,

(Y=OH; X=halide) has become a method of choice for preparing biarylssince it is performed under mild conditions, tolerant of diversefunctionality, and highly selective (Miyaura et al., Synth. Commun. 11:513-519 (1981)). Subsequent developments in metal-catalyzedcross-couplings of organoboron compounds and organic halides haveyielded practical C—C bond forming strategies that complement existingmethodology (Suzuki, Organomet. Chem. 576; 147-168 (1999)). Today theMiyaura-Suzuki reaction is routinely applied in high-throughputscreening for drug discovery (Sammelson and Kurth, Chem. Rev. 101:137-202 (2001)), in the final steps of convergent natural productsyntheses (Chemler and Danishefsky, Org. Lett. 2: 2695-2698 (2000)), andin the synthesis of conjugated organic materials (Schlütter, J. Polym.Sci. A-Polym. Chem. 39: 1533-1556 (2001)).

Arylboron reagents are typically synthesized in a multi-step processsuch as that shown below.

Shorter routes that avoid undesirable halogenated aromatic intermediateswould be attractive. Towards this end, theoretical estimates of B—H andB—C bond enthalpies gave credence to organoborane synthesis via thethermal dehydrogenative coupling of B—H and C—H bonds as shown below(Rablen et al., J. Am. Chem. Soc. 116: 4121-4122 (1994)).

Some key steps in putative catalytic cycles for this process had beenestablished with Hartwig's (Waltz et al., J. Am. Chem. Soc. 117:11357-11358 (1995); Waltz and Hartwig, Science 277: 211-213 (1997)) andMarder's reports of stoichiometric borylations of arenes, alkenes, andalkanes by metal boryl complexes (M-BR₂). Although arene activationproducts were not mentioned, small peaks in the GC-MS trace with massesconsistent with toluene borylation products were assigned in theSupplementary Material to Nguyen et al., Am. Chem. Soc. 115,9329-9330(1993).

While Hartwig has developed elegant photochemical methods forhydrocarbon borylation using catalytic amounts of metal complexes (Chenand Hartwig, Angew. Chem. Int. Ed. 38: 3391-3393 (1999)), thermal,catalytic borylations of unactivated hydrocarbons had not beendocumented prior to our report in 1999 (Iverson and Smith, III, J. Am.Chem. Soc. 121: 7696-7697 (1999)). Since then, borylation of aliphaticand alkyl branched alicyclic hydrocarbons at a primary C—H hydrocarbonbond under thermal conditions using a rhodium catalytic complex whichincludes an electron donor ligand was disclosed in WO 01/64689 A1 andU.S. patent application Ser. No. 0039349 A1, both to Chen et al., andborylation of cyclic hydrocarbons at a secondary or aromatic C—H cyclichydrocarbon bond using the above rhodium catalytic complex was disclosedin WO 01/64688 A1 to Chen et al.

Currently, because C—C coupling of a hydrocarbon requires a multi-stepprocess to produce a borylated hydrocarbon, which is then reacted with ahydrocarbon halide to couple the hydrocarbons, it would be desirable tohave a process wherein the borylation and the C—C coupling are performedin fewer steps or in the same reaction vessel, or both. Therefore, aneed remains for a process for C—C coupling of hydrocarbons which can beperformed in fewer steps and preferably, in the same reaction vessel.

SUMMARY OF THE INVENTION

The present invention provides a process for producing organicsubstituted aromatic compounds (which includes organic substitutedheteroaromatic compounds and biaryl compounds) in a two-step reaction.In the first step, the aromatic compound is borylated in a reactioncomprising a borane or diborane reagent (any boron reagent where theboron reagent contains a B—H, B—B or B—Si bond) and an iridium orrhodium catalytic complex. In the second step, a metal catalystcatalyzes the formation of the organic substituted aromatic compoundfrom the borylated compound and an electrophile such as an aryl ororganic halide, triflate (OSO₂CF₃), or nonaflate (OSO₂C₄F₉). The stepsin the process can be performed in a single reaction vessel or inseparate reaction vessels. The present invention also provides a processfor synthesis of complex polyphenylenes starting from halogenatedaromatic compounds.

Therefore, the present invention provides a process for producing asubstituted aromatic compound, which comprises (a) reacting an aromaticcompound selected from the group consisting of an aryl, a six memberedheteroaromatic compound, and a five membered heteroaromatic compoundwith a borane selected from the group consisting of a borane with a B—H,B—B, and B—Si bond in the presence of a catalytically effective amountof an iridium or rhodium complex with three or more substituents, and anorganic ligand selected from the group consisting of phosphorus, carbon,nitrogen, oxygen, and sulfur organic ligands to form an aromatic boroncompound; and (b) reacting the aromatic boron compound with an organiccompound selected from the group consisting of halide, triflate, andnonaflate in the presence of a catalytically effective amount of a metalcatalyst wherein the aromatic group of the organic compound is coupledto the aromatic group of the aromatic boron compound to produce thesubstituted aromatic compound.

The present invention further provides process for producing an organicsubstituted aryl or heteroaryl compound, which comprises (a) reacting ina reaction vessel a first aromatic compound selected from the groupconsisting of an aryl, a six membered heteroaromatic compound, and afive membered heteroaromatic compound with a borane selected from thegroup consisting of a borane with a B—H, B—B, and B—Si bond in thepresence of a catalytically effective amount of an iridium or rhodiumcomplex with three or more substituents, and an organic ligand selectedfrom the group consisting of phosphorus, carbon, nitrogen, oxygen, andsulfur organic ligands to form an aromatic boron compound; and (b)reacting the aromatic boron compound formed in the reaction vessel withan organic compound selected from the group consisting of halide,triflate, and nonaflate in the presence of a catalytically effectiveamount of a metal catalyst wherein the aromatic group of the organiccompound is coupled to the aromatic group of the aromatic boron compoundto produce the organic substituted aryl or heteroaryl compound.

The present invention further provides a process for producing apolyphenylene, which comprises (a) reacting a mixture of aromaticcompounds with one to five halogen groups and a borane in the presenceof a catalytically effective amount of an iridium or rhodium complexwith three or more substituents, and a phosphorus, carbon, nitrogen,oxygen, or sulfur organic ligand to form a mixture of borylated aromaticcompounds; and (b) reacting the mixture of borylated aromatic compoundsin the presence of a catalytically effective amount of a metal catalystwherein the borylated aromatic compounds in the mixture arecross-coupled to produce the polyphenylene.

The present invention further provides process for producing apolyphenylene, which comprises (a) reacting a mixture of aromaticcompounds and a borane in the presence of a catalytically effectiveamount of an iridium or rhodium complex with three or more substituents,and a phosphorus, carbon, nitrogen, oxygen, or sulfur organic ligand toform a mixture of borylated aromatic compounds; and (b) reacting themixture of borylated aromatic compounds with a mixture of halogenatedaromatic compounds with at least two halogen groups in the presence of acatalytically effective amount of a metal catalyst wherein the borylatedaromatic compounds in the mixture are cross-coupled to the halogenatedaromatic compounds to produce the polyphenylene.

In a further embodiment of the above processes, the three or moresubstituents excludes hydrogen.

In a further embodiment of the above processes, the iridium complex isselected from the group consisting of (Cp*)Ir(H)₂(Me₃P),(Cp*)Ir(H)(BPin)(Me₃P), (Cp*)Ir(H)(C₆H₅)(Me₃P), (Ind)Ir(COD),(Ind)Ir(dppe), (MesH)Ir(BPin)(B(OR)₂)₂, ((R₁)₃P)₃Ir(B(OR₂)₂)₃,(R₁)₂P)₂Ir(BPin)₃, (((R₁)₂P)₃Ir((R₂O)₂B)₃)₂, ((R₁)₃P)₄Ir(BPin),((R₁)₃P)₂Ir(BPin)₃, (MesH)Ir(BPin)₃, and (IrCl(COD))₂, (PMe₃)₂IrH₅,((R₁)₃P)₂IrH₅, and ((R)₃P)₂IrH_(x)(B(OR₂)₂)_(5−x) where x is 0-4,wherein Cp* is 1,2,3,4,5-methylcyclopentadienyl, BPin is pinacolborane,Me is methyl, H is hydrogen, P is phosphorus, Ind is indenyl, COD is1,5-cyclooctadiene, MesH is mesitylene, and wherein R, R₁, and R₂ arehydrogen, linear or branched alkyl containing 1 to 8 carbons, aryl, or acarbon in a cyclic structure.

In a further embodiment of the above processes, the iridium complex is(Ind)Ir(COD) wherein Ind is indenyl and COD is 1,5-cyclooctadiene,(MesH)Ir(BPin)₃ wherein MesH is mesitylene and BPin is pinacolborane, or(IrCl(COD))₂ wherein COD is 1,5-cyclooctadiene.

In a further embodiment of the above processes, the rhodium complex isselected from the group consisting of (Cp*)Rh(H)₂ (Me₃P),(Cp*)Rh(H)(BPin)(Me₃P), (Cp*)Rh(H)(C₆H₅)(Me₃P), and(Cp*)Rh(hexamethylbenzene), wherein Cp* is1,2,3,4,5-methylcyclopentadienyl, BPin is pinacolborane, Me is methyl, His hydrogen, and P is phosphorus.

In a further embodiment of the above processes, the phosphorus organicligand is selected from the group consisting of trimethyl phosphine(PMe₃), 1,2-bis(dimethylphosphino)ethane (dmpe), and1,2-bis(diphenylphosphino)ethane (dppe).

In a further embodiment of the above processes, the borane is a boraneester.

In a further embodiment of the above processes, the borane ispinacolborane. In a further embodiment of the above processes, the metalis palladium.

In a further embodiment of the above processes, the metal catalystcomplex is selected from Pd(PPh₃)₄, Pd₂(dba)₃/P(^(t)Bu)₃, PdCl₂(dppf),Pd(OAc)₂/PCy₃ wherein P is phosphorus and Ph is phenyl, dba isdibenzylideneacetone, ^(t)Bu is tert-butyl, dppf isdiphenylphosphinoferrocene.

OBJECTS

It is an object of the present invention to provide a process forproducing organic substituted aryl compounds and polyphenylenes.

It is a further object of the present invention to provide a two-stepprocess for producing organic substituted aryl compounds andpolyphenylenes.

It is a further object of the present invention to provide a two-stepprocess that can be carried out in a single reaction vessel.

These and other objects of the present invention will becomeincreasingly apparent with reference to the following drawings andpreferred embodiments.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the formulas for precatalysts 1 to 15. CP* is1,2,3,4,5-methylcyclopentadienyl, BPin is pinacolborane, Me is methyl, His hydrogen, P is phosphorus, Ind is indenyl, COD is 1,5-cyclooctadiene,MesH is mesitylene, and wherein R, R₁, and R₂ are each selected from thegroup consisting of hydrogen, linear or branched alkyl containing 1 to 8carbons, aryl, and a carbon in a cyclic structure.

FIG. 2 shows the formulas for precatalysts 16 to 27. Y₄, Y₅, and Y₆ areeach selected from the group consisting of hydrogen, halide, alkyl,aryl, alkoxide (—O(R₁₁)), and amide (—N(R₁₂)(R₁₃)) wherein R₁₁, R₁₂, andR₁₃ are each selected from the group consisting of hydrogen, linearalkyl containing 1 to 8 carbon atoms, branched alkyl containing 1 to 8carbons, and a carbon in a cyclic structure; R₁₄, R₁₅, and R₁₆ are eachselected from the group consisting of hydrogen, linear alkyl, branchedalkyl, and a carbon in a cyclic structure; (PY₇P) is R₁₈R₁₉P—Y₇—PR₂₀R₂₁wherein R₁₈, R₁₉, R₂₀, and R₂₁ are each selected from the groupconsisting of hydrogen, linear alkyl containing 1 to 8 carbon atoms,branched alkyl containing 1 to 8 carbons, and a carbon in a cyclicstructure, and Y₇ is a chain containing 1 to 12 carbons; (PP) is of theformula

wherein R₂₂, R₂₃, R₂₄, R₂₅, R₂₆, R₂₇, R₂₈, and R₂₉ are each selectedfrom the group consisting of alkyl chains, carbocyclic rings, and arylgroups; and BY is a boron moiety.

FIG. 3A shows an example of the one vessel C—H activation/cross couplingreactions as applied to biaryl synthesis.

FIG. 3B shows an example of the one vessel C—H activation/cross couplingreactions as applied to polyphenylene synthesis.

FIG. 4 shows a mechanism for aromatic borylations catalyzed by Ir borylcomplexes.

DETAILED DESCRIPTION OF THE INVENTION

All patents, patent applications, provisional patent applications,government publications, government regulations, and literaturereferences cited in this specification are hereby incorporated herein byreference in their entirety. In case of conflict, the presentdescription, including definitions, will control.

For convenience, wherever the term “aromatic” is used alone, it is to beconstrued to include both aromatic and heteroaromatic compounds selectedfrom the group consisting of aryl, six membered heteroaromaticcompounds, and five membered heteroaromatic compounds and the whereverthe term “organic substituted aromatic compounds” is used alone, it isto be construed to include both organic substituted aromatic andheteroaromatic compounds and biaryl compounds.

The present invention provides a process for producing organicsubstituted aromatic and heteroaromatic compounds including biaryl andbiheteroaryl compounds, which comprises in a first step, reacting anaromatic or heteroaromatic compound with a borane or diborane containinga B—H, B—B or B—Si bond, but preferably a borane ester, in the presenceof a catalytically effective amount of an iridium or rhodium complexwith three or more substituents to produce a borylated aromatic orheteroaromatic intermediate; and in a second step, reacting theborylated aromatic or heteroaromatic intermediate with an organicelectrophile such as an aryl halide, triflate (OSO₂CF₃), or nonaflate(OSO₂C₄F₉), or the like, in the presence of a catalytically effectiveamount of a metal catalyst wherein the aryl group of the aryl or organichalide, triflate, or nonaflate is coupled to the aromatic orheteroaromatic group of the borylated compound to produce the organicsubstituted aromatic or heteroaromatic compound, including biaryl.

The borylation of an aromatic or heteroaromatic substrate and thesubsequent coupling of the borylated aromatic or heteroaromaticintermediate with a second sp²-hybridized halocarbon can be performed ina single reaction vessel as shown in Scheme 1.

The present invention further provides a process for producing apolyphenylene, which in a first step comprises reacting a mixture ofaromatic compounds with one to five halogen groups and a borane ordiborane containing a B—H, B—B or B—Si bond, but preferably a boraneester, in the presence of a catalytically effective amount of an iridiumor rhodium complex with three or more substituents, to form a mixture ofborylated aromatic intermediates; and in a second step, reacting themixture of borylated aromatic intermediates in the presence of acatalytically effective amount of a metal catalyst wherein the borylatedaromatic intermediates in the mixture are cross-coupled to produce thepolyphenylene. See FIG. 3B for an example of the process. The mixture ofaromatic compounds can contain all of one type of aromatic compound or amixture of different types of aromatic compounds.

The present invention further provides a process for producing apolyphenylene, which in a first step comprises reacting a mixture ofaromatic compounds and a borane or diborane containing a B—H, B—B orB—Si bond, but preferably a borane ester, in the presence of acatalytically effective amount of an iridium or rhodium complex withthree or more substituents, to form a mixture of borylated aromaticintermediates; and in a second step, reacting the mixture of borylatedaromatic intermediates with a mixture of halogenated aromatics with atleast two halogen groups in the presence of a catalytically effectiveamount of a metal catalyst wherein the borylated aromatic intermediatesin the mixture are cross-coupled to the halogenated aromatic compoundsto produce the polyphenylene. The mixture of aromatic compounds cancontain all of one type of aromatic compound or a mixture of differenttypes of aromatic compounds. The process is shown in Scheme 2 below.

In Scheme 2, HB(OR)₂ is preferably BPin.

The preferred catalysts for producing the borylated intermediates in thefirst step of the process comprise iridium (Ir) or rhodium (Rh) in acomplex with three or more substituents, preferably excluding hydrogen,bonded to the Ir or Rh and preferably, further including a phosphorusorganic ligand, which is at least in part bonded to the Ir or Rh. Theprocess for forming B—C bonds between boranes and sp²-hybridized C—Hbonds to produce organoboron intermediates such as ring-substitutedarenes (or aryl boronate esters and acids) according is shown in Scheme3.

The direct route to aromatic or heteroaromatic boronate esters and acidsin the first step produces intermediates which are versatile transferreagents in the second step of the process of the present invention. Theboron in these transfer reagents serves as a mask for a broad range ofheteroatoms and functional groups during the catalytic cross-couplingreactions of C—B and C—X (X is Cl, Br, I, triflate, nonaflate) groups inthe second step to yield new C—C bonds as shown in scheme 4.

The above two-step process is particularly useful in the pharmaceuticalindustry for drug manufacturing and for synthesis of compounds in drugdiscovery. Thus, the present invention further provides catalyst kitsthat can be used for general couplings in drug discovery applications.

Preferably, the B—C bond-forming reaction between a borane and ansp²-hybridized C—H bond to produce a ring substituted arene in the firststep is catalyzed by a catalyst comprising Ir and Rh in a complex withthree or more substituents, preferably excluding hydrogen as asubstituent, bonded to the Ir or Rh and further preferably, an organicligand selected from the group consisting of phosphorus, carbon,nitrogen, oxygen, and sulfur organic ligands. For example, phosphorusorganic ligands, organic amines, imines, nitrogen heterocycles, ethers,and the like. Preferably, the ligand is in a molar ratio between about 1to 3 and 1 to 1, wherein the organic ligand is at least in part bondedto the iridium or rhodium.

Effective precatalysts for forming the B—C bonds can be grouped into twofamilies: those that contain cyclopentadienyl (Cp*, C₅R₅ wherein R isCH₃) or indenyl (Ind, C₉R₇ wherein R is H) ligands and those thatcontain phosphine ligands. Included are compounds that contain both theCp* and the Ind ligands and the phosphine ligands.

Preferably, the Ir catalytic composition for the first step of theprocess comprises one of the following: (ArH)Ir(BY)₃ wherein ArH isselected from the group consisting of aromatic, heteroaromatic,polyaromatic, and heteropolyaromatic hydrocarbon and wherein BY is aboron moiety; (MesH)Ir(BY)₃ wherein MesH is mesitylene and wherein BY isa boron moiety; (P(Y₄)(Y₅)(Y₆))₃Ir (H)_(n)(BY)_(3−n) wherein Y₄, Y₅, andY₆ are each selected from the group consisting of hydrogen, halide,alkyl, aryl, alkoxide (—O(R₁₁)), and amide (—N(R₁₂) (R₁₃)) wherein R₁₁,R₁₂, and R₁₃ are each selected from the group consisting of hydrogen,linear alkyl containing 1 to 8 carbon atoms, branched alkyl containing 1to 8 carbons, and a carbon in a cyclic structure, wherein n is 0, 1, or2, and wherein BY is a boron moiety; (P(R₁₄)(R₁₅)(R₁₆))₃Ir(H)_(n)(BY)_(3−n) wherein R₁₄, R₁₅, and R₁₆ are each selected from thegroup consisting of hydrogen, linear alkyl, branched alkyl, and a carbonin a cyclic structure, wherein n is 0, 1, or 2, and wherein BY is aboron moiety; (P(Y₄)(Y₅)(Y₆))₃Ir (H)(R₁₃)(BY) wherein Y₄, Y₅, and Y₆ areas above, wherein R₁₃ is selected from the group consisting of a linearalkyl containing 1 to 8 carbon atoms, branched alkyl containing 1 to 8carbons, aryl, and a carbon in a cyclic structure, and wherein BY is aboron moiety; (P(R₁₄)(R₁₅)(R₁₆) )₃Ir (H)(R₁₇)(BY) wherein R₁₄, R₁₅, andR₁₆ are as above; R₁₇ is as above, and wherein BY is a boron moiety;{(PY₇P) Ir(BY)₃}₂ (μ₂-(PY₇P)) (16) wherein BY is a boron moiety, wherein(PY₇P) is R₁₈R₁₉P—Y₇—PR₂₀R₂₁ wherein R₁₈, R₁₉, R₂₀, and R₂₁ are eachselected from the group consisting of hydrogen, linear alkyl containing1 to 8 carbon atoms, branched alkyl containing 1 to 8 carbons, and acarbon in a cyclic structure, and wherein Y₇ is a chain containing 1 to12 carbons; (PY₇P)(P(Y₄)(Y₅)(Y₆))Ir(BY)₃ (17) wherein BY is a boronmoiety, wherein Y₄, Y₅, and Y₆ are as above, and wherein (PY₇P) is asabove; (PY₇P)(P(R₁₀)(R₁₁)(R₁₂))Ir(BY)₃ (18) wherein BY is a boronmoiety, wherein R₁₄, R₁₅, and R₁₆ are as above, wherein (PY₇P) is asabove; {(PP)Ir(BY)₃}₂(μ₂-(PP)) (19) wherein BY is a boron moiety andwherein (PP) is of the formula

wherein R₂₂, R₂₃, R₂₄, R₂₅, R₂₆, R₂₇, R₂₈, and R₂₉ are each selectedfrom the group consisting of alkyl chains, carbocyclic rings, and arylgroups; (PP)(P(Y₄)(Y₅)(Y₆))Ir(BY)₃ (20) wherein BY is a boron moiety,wherein Y₄, Y₅, and Y₆ are as above, and wherein (PP) is as above;(PP)(P(R₁₄)(R₁₅)(R₁₆))Ir(BY)₃ (21) wherein BY is a boron moiety, whereinR₁₄, R₁₅, and R₁₆ are as above, and wherein (PP) is as above;(PY₇P)Ir(BY)₃ (22) wherein BY is a boron moiety, and wherein and (PY₇P)is as above; (PP)Ir(BY)₃ (23) wherein BY is a boron moiety, and wherein(PP) is as above; (P(Y₄)(Y₅)(Y₆))₄Ir(BY) wherein Y₄, Y₅, and Y₆ are asabove and BY is a boron moiety; (P(R₁₄)(R₁₅)(R₁₆))₄Ir(BY) wherein R₁₄,R₁₅, and R₁₆ are as above and BY is a boron moiety;(PY₇P)(P(Y₄)(Y₅)(Y₆))₂Ir(BY)(24) wherein BY is a boron moiety, whereinY₄, Y₅, and Y₆ are above, and wherein (PY₇P) is as above;(PP)(P(Y₄)(Y₅)(Y₆))₂Ir(BY)(25) wherein BY is a boron moiety, wherein Y₄,Y₅, and Y₆ are as above, and wherein (PP) is as above;(PY₇P)(P(R₁₄)(R₁₅)(R₁₆))₂Ir(BY) (26) wherein BY is a boron moiety, R₁₄,R₁₅, and R₁₇ are as above, and wherein (PY₇P) is as above;(PP)(P(R₁₄)(R₁₅)(R₁₆))₂Ir(BY) (27) wherein BY is a boron moiety, whereinR₁₄, R₁₅, and R₁₆ are as above, and wherein (PP) is as above.

Examples of catalytic compositions comprising iridium include thoseselected from the group consisting of (Cp*)Ir(H)₂(Me₃P) (1),(Cp*)Ir(H)(BPin)(Me₃P) (2), (CP*)Ir(H)(C₆H₅)(Me₃P) (3), (Ind)Ir(COD)(8), (MesH)Ir(BPin)(B(OR)₂) (9), ((R₁)₃P)₃Ir(B(OR₂)₂)₃ (10),(R₁)₂P)₂Ir(BPin)₃ (11), (((R₁)₂P)₃Ir((R₂O)₂B)₃)₂ (12), ((R₁)₃P)₄Ir(BPin)(13), ((R₁)₂P)₂Ir(BPin)₃ (14), (MesH)Ir(BPin)₃ (9 wherein B(OR)₂ isBPin), IrCl(COD) (15) and (IrCl(COD))₂, wherein CP* is1,2,3,4,5-methylcyclopentadienyl, BPin is pinacolborane, Me is methyl, His hydrogen, P is phosphorus, Ind is indenyl, COD is 1,5-cyclooctadiene,MesH is mesitylene, and wherein R, R₁, and R₂ are each selected from thegroup consisting of hydrogen, linear or branched alkyl containing 1 to 8carbons, aryl, and a carbon in a cyclic structure.

Preferably, the Rh catalytic composition for the first step comprisesone of the following: (Cp′)(P(Y₄)(Y₅)(Y₆))Rh(H)_(n)(BY)_(2−n) whereinY₄, Y₅, and Y₆ are as above, wherein n is 0 or 1, wherein BY is a boronmoiety, and wherein Cp′ is of the formula

wherein R₃₀, R₃₁, R₃₂, R₃₃, and R₃₄ are each selected from the groupconsisting of hydrogen, alkyl chains, carbocyclic rings, and arylgroups; and (Cp′)(P(R₁₄(R₁₅)(R₁₆))Rh(H)_(n)(BY)_(2−n), wherein R₁₄, R₁₅,and R₁₆ are as above; n is 0 or 1, wherein BY is a boron moiety; andwherein Cp′ is as above.

Examples of catalytic compositions comprising rhodium include thoseselected from the group consisting of (Cp*)Rh(H)₂(Me₃P) (4),(Cp*)Rh(H)(BPin)(Me₃P) (5), (CP*)Rh(H)(C₆H₅)(Me₃P) (6), and(Cp*)Rh(hexamethylbenzene) (7), wherein CP* is1,2,3,4,5-methylcyclopentadienyl, BPin is pinacolborane, Me is methyl, His hydrogen, and P is phosphorus.

In the above catalytic compositions, preferably the BY boron moietyselected from the group consisting of

wherein R₁, R₂, R₃, R₄, R₅, and R₆ are each selected from the groupconsisting of hydrogen, linear alkyl containing 1 to 8 carbon atoms,branched alkyl containing 1 to 8 carbons, and a carbon in a cyclicstructure. FIGS. 1 and 2 show the structures of precatalysts 1 to 15 and16 to 27, respectively.

While the precatalysts can under particular reaction conditions catalyzethe borylation of particular ring-substituted arenes, the reactionsproceed more efficiently when an organic ligand such as phosphineligands (phosphorus organic ligands) are included in the reactionmixture. The addition of phosphine ligands to the reaction generatesactive catalysts which can produce ring-substituted arene boranes (arylboronate esters and acids) with low catalyst loading. The fact thatphosphine-containing species can catalyze borylation is importantbecause numerous phosphines are commercially available. Furthermore, theselectivities of the borylation can be altered as a function of thephosphine ligand that is added. Examples of phosphine ligands include,but are not limited to, trimethyl phosphine (PMe₃),1,2-bis(dimethylphosphino)ethane (dmpe),1,2-bis(diphenylphosphino)ethane (dppe), Cy₃P, and Ph₃P.

For example, precatalyst 8 can be obtained in two high-yielding stepsfrom the common iridium starting material, IrCl₃(H₂O)_(x). Precatalyst 9can be prepared by reacting 8 with approximately 5 equivalents ofpinacolborane (HBPin) in mesitylene solvent. It was discovered thatcommercially available precatalyst 15 will also catalyze borylations.While all of the precatalysts have similar activities for manysubstrates, borylations of particular arenes exhibit a remarkableprecatalyst dependence.

In the absence of phosphine ligands, compound 8 catalyzes the borylationof benzene by HBPin, but relatively high catalyst loading and longreaction times are required to prepare PhBPin in reasonable yields. Attemperatures above 80° C., decomposition to Ir metal occurs, which haltscatalysis. Compound 9 is not effective in catalysis without the additionof phosphine.

Addition of phosphine ligands to solutions of compound 8 and 9 generatesactive catalysts for the production of aryl boronic esters with lowcatalyst loading as illustrated for the examples in FIG. 1. The factthat phosphine-containing species can catalyze borylation is importantbecause numerous phosphines are commercially available. Consequently,the selectivities can be altered as a function of the phosphine that isadded.

Another virtue of the present invention is that a broad range ofheteroatoms and functional groups are inert under borylation conditionsas shown in Scheme 5.

Given that Grignard reagents react with several of these groups and Pdcatalyzes the formation of ArBPin from ArBr and HBPin, the functionalgroup tolerance for the Ir-catalyzed chemistry is remarkable. Underappropriate conditions, even iodobenzene can be borylated without iodidereduction. In this instance, no conversion was observed when usingprecatalyst 8, whereas precatalyst 9 gives the borylated products in 95%yield as shown in Scheme 6.

Therefore, the present substrate compatibility, which is alreadyremarkably broad, is expected to expand with further improvements to thepresent invention.

For monosubstituted arenes, mixtures of meta and para borylated productsare obtained. In contrast to the known Rh complexes that catalyzearomatic borylation, the meta:para ratio deviates significantly from2:1. For most substrates, this ratio exceeds 3:1 and data for anisoleare shown in Table 1.

TABLE 1 Isomer distributions for catalytic borylations of anisole

Entry Catalyst Temp (° C.) Time (h) o:m:p 1 2 mol % 8/2 PMe₃ 150 299:74:17 2 2 mol % 9/2 PMe₃ 150 41 8:75:17 3 2 mol % 8/dppe 150 223:76:21 4 2 mol % 9/dppe 150 51 3:78:20 5 2 mol % 8/dppe 100 22 2:80:186 2 mol % 3/dppe 100 18 2:80:18 7 2 mol % 9 150 3 12:53:36^(a) 8 2 mol %8/PMe₃ 150 29 2:57:40 9 2 mol % 9/PMe₃ 150 40 3:67:30 ^(a)Lowconversion. o is ortho, m is meta, and p is para. Dppe is1,2-bis(diphenylphosphino)ethaneIt is noteworthy that the para isomer is more favored for entries 7 and8, where the meta:para ratio is significantly less than 2:1. These datashow that while there is a steric bias against ortho borylation, themeta:para ratio is sensitive to the type and amount of phosphine ligandsthat are added. For dppe, the activity at 100° C. is relatively high,and the reaction is complete in less time than at 150° C.

With the exception of F, and amide functional groups in some Rhcatalyzed reactions, borylation at positions that are ortho tofunctional groups are avoided. Thus, 1,3-substituted aromatics can beselectively borylated at the 5′ position. This is the hardest positionto selectively activate by traditional aromatic substitution chemistryand for electron rich arenes, there are no general methods for preparingderivatives from the 1,3-substituted arenes.

Furthermore, multiple borylation of 1,3-substituted arenes does notoccur to a significant extent, which means that equimolar quantities ofborane and arene give aromatic boronic esters in high yield in theabsence of solvent. Substrates that have been successfully converted toboronate esters under these conditions are shown in scheme 7.

For fluorinated benzenes, the borylation at ortho positions occursreadily. Hence, C₆HF₅ and 1,3,5-trifluorobenzene give mono andtriborylated products, respectively, as shown in Scheme 8.

It is noteworthy that present Rh catalysts are not compatible withhalide functionalities and substantial quantities of dehalogenated anddiborylated products are observed. We extended the chemistry tofive-membered rings and heterocycles as shown by the borylation of aprotected pyrrole and 2,6-lutidine in Scheme 9.

The borylation of aromatic and heteroaromatic compounds and thecatalysts suitable for the borylation are disclosed in the commonlyowned U.S. Application, which was filed Jul. 13, 2002, and which claimspriority to U.S. Provisional 60/305,107 filed Jul. 13, 2001.

In the second step of the process of the present invention, theborylated intermediate is reacted with a halogenated aryl or organic,triflate, or nonaflate compound in the presence of a metal catalystwhich cross-couples the C at the C—B bond and the C at the C-halogenbond to produce the substituted aromatic, heteroaromatic, biaryl, orbiheteroaryl compound. In a preferred embodiment, the metal comprisingthe metal catalyst is palladium. Examples of Pd catalysts which aresuitable for the cross-coupling include, but are not limited to,Pd(PPh3)₄/P(^(t)Bu)₃, PdCl₃(dppf) Pd(OAc)₂/PCy₃ wherein P is phosphorusand Ph is phenyl, dba is dibenzylideneacetone, ^(t)Bu is tert-butyl, anddppf is diphenylphosphinoferrocene.

The process for making organic substituted aromatic and heteroaromaticcompounds, including biaryls and biheteroaryls, avoids many of thelimitations of the prior art because (1) the borylation reactions can becarried out in neat substrates, thereby avoiding ethereal solvents, (2)since the C—H bonds are selectively activated, halogenation of arenesand conversions to Grignard or organolithium reagents are eliminated,(3) the only byproducts of the borylation reaction are hydrogen, whichis easily removed, and the catalyst, which is present in lowconcentrations, can be recovered, (4) the process of the presentinvention tolerates a broad range of functional groups, (6) activecatalysts are generated from common precursors and selectivities can bealtered by adding commercially available ligands such as alkylphosphines, (7) particular substitution patterns which are notoriouslydifficult to achieve using prior art aromatic substitution chemistry canbe obtained in one step starting from inexpensive starting materials,and (8) Ir metal is relatively inert, Ir complexes generally have lowtoxicity, and Ir metal recovered from the reactions can be recoveredfrom the reaction waste and recycled. Furthermore, the process can beused to make chiral organic substituted aromatic compounds.

The following examples are intended to promote a further understandingof the present invention.

EXAMPLE 1

The process of the present invention was inspired by Bergman's (Science223: 902-908 (1984)) and Jones and Feher's (Acc. Chem. Res. 22: 91-100(1989)) fundamental studies of hydrocarbon (R—H, R=alkyl or aryl)activation by Cp*(Me₃)M^(I) intermediates (M=Ir, Rh; Cp* η⁵-C₅Me₅),which produce Cp*(PMe₃)M^(III)(H)(R) where M—H and M—R bonds result fromR—H scission.

While investigating stoichiometric B—C bond formation in reactionsbetween Cp*(PMe₃)Ir(H)(Ph) and pinacolborane (HBPin), we found thatsubstantial quantities of arylboron products were produced fromcatalytic solvent activation. The major metal-containing product in thisreaction, Cp*(PMe₃)Ir(H)(BPin)(2), was a precatalyst for benzeneborylation with an effective turnover number (TON) corresponding to theformation of three molecules of PhBPin per molecule of 2 (Iverson andSmith, III, J. Am. Chem. Soc. 121: 7696-7697 (1999)). Subsequently,Hartwig and co-workers reported alkane and arene borylations utilizingmuch more active Rh precatalysts, such as Cp*Rh(η⁴-C₆Me₆) (7)(Chen etal., Science 287: 1995-1997 (2000)).

A comparison of precatalysts 2 and 7 in borylations of varioussubstituted arenes revealed that the Ir system was more selectivetowards arene C—H activation (Cho et al., J. Am. Chem. Soc. 122:12868-12869 (2000)). Given the importance of selectivity in chemicalsynthesis, these findings spurred a detailed investigation of theoriginal Ir system. Those results are described herein.

Compound 2 is stable in benzene solutions after prolonged thermolysis,which eliminates several mechanistic possibilities, including PMe₃dissociation to generate Cp*Ir(H)(BPin), an analog of proposedintermediates in the Rh system. However, added PMe₃ strongly inhibitscatalysis where HBPin is present. This indicated that small quantitiesof phosphine-Ir^(V) species could be active. SinceCp*IrH_(4−x)(BPin)_(x) species (x=1, 2) form in the thermolysis ofCP*IrH₄ and HBPin (Kawamura and Hartwig, J. Am. Chem. Soc. 123:8422-8423 (2001)), anisole borylations with identical loadings ofCP*IrH₄ and 2 were compared. From this experiment,Cp*IrH_(4−x)(BPin)_(x) intermediates can be eliminated because they arenot kinetically competent for catalysis and the borylationregioselectivities for Cp*IrH₄ and 2 differ substantially. At 150° C.,the following isomer ratios were obtained for anisole borylation with 20mol % precatalyst loadings: Cp*IrH₄, o:m:p=3:49:48; 2 o:m:p=2:79:19.

Exclusion of a simple phosphine dissociative pathway narrows theplausible catalysts to two choices: (i) Ir phosphine species arisingfrom Cp* loss or (ii) species where both Cp* and PMe₃ have been lost.The latter possibility was intriguing in light of Marder's synthesis of(η⁶-arene)Ir(BCat)₃ complexes (Cat=ortho-catecholate) from (Ind)Ir(COD)(3, Ind η⁵-C₉H₇, COD=1,5-cyclooctadiene) and HBCat in arene solvents(10). Using an analogous route, we prepared (η⁶-mesitylene)Ir(BPin)₃ (9in which B(OR)₂ is BPin) in 19% yield from (Ind)Ir(COD) (8) and HBPin(Compound 9 has been prepared as an analytically pure white solid.Relevant spectroscopic data included ¹H NMR (C₆D₆) δ1.33 (s,36 H,BO₂C₆H₁₂), 2.23 (s, 9H, C₆H₃(CH₃)₃), 5.62 (s, 3H, C₆H₃(CH₃)₃). ¹¹B NMR(C₆D₆) δ 32.5. ¹³C NMR (C₆D₆) δ 19.68, 25.73, 80.95, 96,97, 118.05).Compound 9 reacted with benzene at 150° C. to produce Ir metal and threeequivalents of C₆H₅BPin, but did not catalyze C₆H₅BPin formation frombenzene and HBPin. Thus, it appears that phosphines or related donorligands are required for catalysis.

Utilizing the lability of the mesitylene ligand in 9, Ir phosphinespecies were generated in situ from 9 and appropriate phosphines andsubsequently screened for activity. Borylation using 2 mol % 9 and 4 mol% PMe₃ was viable (Table 1, entry 1), and both catalytic activity andTONs for benzene borylation increased dramatically relative toprecatalyst 2. Borylation rates were appreciable when P:Ir<3:1, butdecreased dramatically when P:Ir ratio equals or exceeds 3:1.

TABLE 1^(a) Arene: Temp Time Yield Ent. Sub. HBPin Prod. Cat. Ligand (°C.) (h) (%)  1 C₆H₆ 16:1 PhBPin (MeSH) Ir (BPin)₃ PMe₃ 150 15 98^(b) (9) 2 C₆H₆ 16:1 PhBPin (Ind)Ir(COD) PMe₃ 150 18 88^(b) (8)  3 C₆H₆ 16:1PhBPin 8 dppe 150 2 95^(b)  4 C₆H₆ 16:1 PhBPin 8 dmpe 150 2 84  5 C₆H₆16:1 PhBPin 0.02 mol % 8 dmpe 150 61 90^(b)  6 C₆H₆ 16:1 PhBPin(IrCl(COD))₂ dmpe 150 8 74^(b)  7

4:1

8 dmpe 150 1 63  8

1:5

8 dmpe 150 62 76  9

4:1

8 dppe 100 3 81 10

1:1.5

8 dppe 100 14 89 11

1:1.5

8 dppe 100 17 92 12^(c)

1:2

8 dppe 100 4 69 13

10:1 — 8 dppe 100 60 — 14

10:1

9 dppe 100 57 77 15^(c)

1:2

8 dppe 100 25 95 16

1:3

8 dmpe 150 95 82 ^(a)Reactions run in neat arene, Ir = 2 mol %, P: Ir =2:1, and yields are reported for isolated materials unless otherwisenoted. (COD = 1,5,-cyclooctadiene, dmpe = Me₂PCH₂CH₂PMe₂, dppe =Ph₂PCH₂CH₂PPh₂). ^(b)GC yield base on HBPin. ^(c)Reactions run incyclohexane.

The low isolated yields of 9 hampered screening efforts and precludedpractical applications despite the dramatic improvement in catalyticactivity. Hence, we sought alternative means for generating activecatalysts. Since NMR spectra indicated quantitative generation of 9 from8, in situ generation of active catalysts by phosphine addition to 8 wasexamined. Compound 8 was synthesized in 86% yield from indenyl lithiumand (IrCl(COD))₂ (Merola and Kacmarcik, Organometallics 8: 778-784(1989)). This approach was successful and results for benzeneborylations are shown in Table 1 (entries 2-5). Chelating phosphinessubstantially increased activity and TONs as highlighted for1,2-bis(dimethylphosphino)ethane (dmpe) where the effective TON of 4500(entry 5) represented an improvement of more than 1000-fold overprecatalyst 2. In addition, active catalysts were generated fromcommercially available sources such as (IrCl(COD))₂ (entry 6).

If the primary active species generated by PMe₃ addition to 8 and 9 areidentical to those generated from 2, borylations of substituted benzenesshould exhibit similar regio- and chemoselectivities. Anisole is auseful substrate for probing regioselectivity and the meta:para ratiosdetermined from borylations by active species generated by PMe₃ additionto 8 and 9 are similar to those for 2 (For catalysts generated from 4mol % PMe₃ and 2 mol % 8 or 9, the following isomer ratios were obtainedfor anisole borylation at 150° C.: 8, o:m:p=9:74:17; 9, o:m:p=8:75:17.For 8 and 9, ortho borylation increases slightly, which could signify aminor pathway that is not accessible from 2).

To assess chemoselectivities, the ratios of arene to benzylic activationin M-xylene were examined. The selectivities of catalysts generated from8 (13:1) and 9 (12:1) were diminished relative to the selectivity ofprecatalyst 2 (35:1). Nevertheless, the Ir catalysts were more selectivefor arene activation than the Rh catalyst, 7, where the selectivity was7:1 (Cho et al., J. Am. Chem. Soc. 122: 12868-12869 (2000)); a Rhcatalyst that is highly selective for benzylic borylation has beenrecently reported (Shimada et al., Angew. Chem., Int. Ed. 40: 2168-2171(2001)), and the addition of one equivalent of the chelating phosphine,1,2-bis(diphenylphosphino)ethane (dppe) per equivalent of 8 or 9generated catalysts where the arene to benzylic selectivities exceeded142:1.

Dramatic differences in chemoselectivities between Ir and Rh catalystswere found for halogenated substrates, where the Ir catalystspreferentially activated C—H bonds. A representative procedure forborylation is given for entry 10 of Table 1. Briefly, in a glove boxunder N₂, compound 8 (57 mg, 0.14 mmol) and dppe (54 mg, 0.14 mmol) weredissolved in HBPin (1.30 g. 10.2 mmol). The solution was transferred toa thick-walled air-free flask containing 1,3-dichlorobenzene (1.00 g,6.80 mmol). The clear yellow solution was heated at 100° C. under N₂ andmonitored by GC-FID. After 14 hours, the reaction mixture was pumpeddown to obtain a brown oil, which was vacuum distilled at 93-94° C.(0.03 mmHg). The resulting oil was then dissolved in Et₂O (10 mL) andwashed with water (5×100 mL). After drying over MgSO₄, ether was removedunder high-vacuum to give 1.65 g (89% yield) of colorless1,3,5-C₆H₃Cl₂BPin (mp 36-38° C.: ¹H NMR (500 MHz. CDCl₃) δ 1.32 (s,12H), 7.41 (t, J=2.0 Hz, 1H), 7.63 (d, J=2.0 Hz, 2H). ¹³C NMR (125 MHz,CDCl₃) δ 24.82, 84.49, 131.1, 133.7, 134.7. ¹¹B NMR (CDCl₃) δ 30). Goodyields of mono- or tri-borylated products of 1,3,5-trifluorobenzene wereobtained by adjusting the arene:HBPin ratio (Table 1, entries 7 and 8).In contrast, previous attempts to effect multiple borylations of1,3,5-trifluorobenzene using the Rh catalyst 7 led to increaseddefluorination (Cho et al., J. Am. Chem. Soc. 122: 12868-12869 (2000)).Borylations of aromatics with heavier halogen substituents provided aneven starker contrast between Ir and Rh catalysts. For example, Ircatalyzed borylations of 1,3-dichlorobenzene and 1,3-dibromobenzenegenerate meta functionalized products in high yields (entries 10 and11), while dehalogenation is the dominant pathway in Rh catalyzedreactions. Dechlorination was observed during attempted silylations of1,3-dichlorobenzene using closely related Rh catalysts (Ezbiansky etal., Organometallics 17: 1455-1457 (1998). The finding that aromaticC-halogen bonds survived in the Ir catalyzed reactions contrasted thePd-catalyzed reactions of boranes and aryl bromides where the C—Br bondswere converted to C—B or C—H bonds (Murata, et al., J. Org. Chem. 65:164-168 (2000)). Entry 12 illustrates an extension of meta selectiveborylation to a halogenated heterocycle.

Since aryl iodides have the weakest carbon-hydrogen bonds, they are mostsusceptible towards reductive cleavage by transition metals. Hence, itis not surprising that the Ir catalysts generated from 8 wereineffective in aromatic borylation of iodobenzene (Table I, entry 13).However, iodobenzene and HBPin reacted smoothly to yield a mixture ofC₆H₄I(BPin) isomers when active catalysts were generated from theIr^(III) source, 9, and dppe (entry 14). Thus, Ir catalysts arecompatible with the entire range of aryl halides. Furthermore,functional group tolerance that was previously found in Rh catalyzedborylations extends to Ir catalyzed reactions (viz., ester compatibilityin entry 15) and Ir selectively borylates symmetrical 1,2-substitutedarenes at the 4-position (entry 16).

The remarkable selectivity of Ir borylation catalysts for aromatic C—Hbonds suggested that Ir byproducts might not interfere in subsequentreactions of the arylboron products. Thus, we envisaged one-vesselelaborations of arene C—H bonds where catalytic borylations are followedby other metal-catalyzed events in a catalytic cascade. For a Zr/Pdcatalyzed route to substituted biphenyls and terphenyls (See Frid etal., J. Am. Chem. Soc. 121: 9469-9470 (1999)). To assess thispossibility, the union of catalytic borylations and Miyaura-Suzukicross-couplings for one-vessel biaryl synthesis from C—H and C—Xprecursors was attempted. As shown in FIG. 3A, the biaryl product can beprepared in good yield from the in situ Pd-catalyzed cross-coupling of3-bromotoluene with 1,3,5-C₆H₃Cl2(BPin), generated by Ir-catalyzedborylation of 1,3-dichlorobenzene with HBPin. An interesting extensionof Ir/Pd tandem catalysis highlighting Ir compatibility with halogenatedaromatics is shown in FIG. 3B. The specific target was a hyperbranchedpolyphenylene that Kim and Webster prepared via Pd catalyzed coupling ofthe bromo/boronic acid monomer, 1,3,5-C₆H₃Br₂(B(OH)₂) (Kim and Webster,Macromolec. 25: 5561-5572 (1992)). Using Ir/Pd tandem catalysis,material with nearly identical NMR (¹³C, ¹H) and GPC data was obtainedfrom HBPin and 1,3-dibromobenzene in a one-vessel reaction. For thematerial in FIG. 3B, M_(ω)=6374 and M_(n)=3460 as compared to thepreviously reported values of M_(ω)=5750 and M_(n)=3820 (Kim andWebster, Macromolec. 25: 5561-5572 (1992)).

From a mechanistic standpoint, catalytic cycles involving oxidativeaddition/reductive elimination from Ir^(I/III) and/or Ir^(III/V)intermediates are consistent with the results herein. Within thiscontext, we considered Ir^(I) and Ir^(III) boryl intermediates to be themost likely C—H activating species in the Ir^(I/III) and Ir^(III/V)cycles, respectively. Hence, the Ir^(I) and Ir^(III) boryl complexes,Ir(BPin)(PMe₃)₄ and fac-Ir(BPin)₃(PMe₃)₃, were prepared in order toevaluate their stoichiometric reactions with arenes.

Compounds Ir(BPin)(PMe₃)₄ and fac-Ir(BPin)₃(PMe₃)₃ have been fullycharacterized as shown by the following spectroscopic data:Ir(BPin)(PMe₃)₄, ¹H NMR (C₆D₆, 25° C.) δ 1.24 (s, 12H, BO₂C₆H₁₂), 1.58(b, 36H, PCCH₃)₃). ¹¹B NMR (C₆D₆) δ 38. ³¹P {¹H} NMR (C₆D₆) δ −57.5;fac-Ir(BPin)₃(PMe₃)₃, ¹H NMR (C₆D₆) δ 1.34 (S, 36H, BO₂C₆H₁₂), 1.52 (m,27H, P(CH₃)₃). ¹¹B NMR (C₆D₆) δ 36.0. ³¹P{¹H} NMR (C₆D₆) δ −64. Inreactions with arenes, compounds Ir(BPin)(PMe₃)₄ andfac-Ir(BPin)₃(PMe₃)₃ both reacted cleanly with benzene to produce PhBPinand the corresponding hydride complexes shown below, which wasconsistent with the idea that Ir^(I) or Ir^(III) species can effectarene borylation; however, the arene products from stoichiometricreactions of Ir(BPin)(PMe₃)₄ and fac-Ir(BPin)₃(PMe₃)₃ with iodobenzenediffered substantially.

Specifically, compound Ir(BPin)(PMe₃)₄ reacted rapidly with iodobenzeneat room temperature, but isomers of C₆H₄I(BPin) were not detected, evenafter prolonged thermolysis. Conversely, thermolysis offac-Ir(BPin)₃(PMe₃)₃ in iodobenzene produced m- and p-C₆H₄I(BPin) in 54%yield, based on fac-Ir(BPin)₃(PMe₃)₃, in addition to a 45% yield ofPhBPin.

Since conversion rates in catalytic reactions plummet when P:Ir ratiosequal or exceed 3:1, the observation that Ir(BPin)(PMe₃)₄ andfac-Ir(BPin)₃(PMe₃)₃ were not kinetically competent for catalysis wasexpected. However, this does not exclude the possibility that identicalintermediates are generated in the stoichiometric and catalyticreactions. Instead, generation of appropriate intermediates undercatalytic conditions could simply be more efficient. Nevertheless, thestoichiometric transformations lend credence to either Ir^(I) orIr^(III) species mediating C—H activations under catalytic conditions.The reactions of Ir(BPin)(PMe₃)₄ and fac-Ir(BPin)₃(PMe₃)₃ withiodobenzene have greater mechanistic implications. For example, theabsence of C₆H₄I(BPin) products in thermolysis of Ir(BPin)(PMe₃)₄mirrored the failed attempt to borylate iodobenzene using the Ir^(I)precatalyst 8 (entry 13). The reactivity of fac-Ir(BPin)₃(PMe₃)₃suggests that an Ir^(III) intermediate may activate C—H bonds in thepresence of C—I bonds, but the chemistry of Ir(BPin)(PMe₃)₄ is moreimportant because it essentially excludes the participation of Ir^(I)species in the successful borylation of iodobenzene using the Ir^(III)precatalyst 9 (entry 14).

Although catalytic processes involving Ir^(I) intermediates have notbeen categorically excluded, we presently prefer the simplifiedmechanism involving Ir^(III) and Ir^(V) intermediates in FIG. 4 for thefollowing reasons: (i) the correlations between stoichiometric andcatalytic borylations of iodobenzene by Ir^(I) and Ir^(III) argueagainst an Ir^(I/III) mechanism, (ii) the catalytic inhibition when P:Irratios equal or exceed 3:1 and the slow borylation rates for the18-electron Ir^(III) complex fac-Ir(BPin)₃(PMe₃)₃ are consistent withthe generation of a reactive 16-electron bisphosphine Ir^(III)intermediate from an 18-electron bisphosphine Ir^(V) resting state,(iii) since chelating phosphines generally inhibit phosphinedissociative pathways, the catalytic activity with chelating phosphinessupports the viability of bisphosphine intermediates, and (iv) the18-electron bisphosphine compound, Ir(PMe₃)₂H₅, is an effectiveprecatalyst for borylation. A more definitive characterization of thecatalytic manifold is underway.

In summary, an investigation of the original Ir catalytic system, whosepromising selectivities could not be practically implemented due toextremely low effective TONs, has produced a family of efficientborylation catalysts with remarkable regio- and chemoselectivities. Inaddition to providing a direct route to aryl and heteroaryl boroncompounds from boranes and arenes, the viability of a tandem catalyticcascade where the first step is an Ir catalyzed aromatic borylation hasbeen demonstrated. We are optimistic that extensions of these findingswill have significant synthetic applications.

EXAMPLE 2

This example shows a two-step, one-vessel process for synthesis of thebiaryl 3,5-bis(trifluoromethyl)biphenyl from1,3-bis(trifluoromethyl)benzene, a borane (HBPin), and iodobenzene. Anarylboronate ester was produced using an Ir catalyst and thearylboronate was subsequently coupled to the iodobenzene using apalladium catalyst.

In a glove box, HBPin (448 mg, 3.50 mmol) was added to a mixture of1,3-bis(trifluoromethyl)benzene (500 mg, 1.34 mmol), (COD) Ir(Indenyl)(19.5 mg, 0.047 mmol), and dppe (18.6 mg, 0.047 mmol) in a smallair-free flask equipped with a stir bar. The flask was then sealed andheated at 100° C. for 16 hours.

Afterwards, the reaction solution was allowed to cool to roomtemperature and Pd₂(dba)₃ (42.8 mg, 0.047 mmol), P(tBu)₃ (28.3 mg 0.140mmol), iodobenzene (476 mg, 2.24 mmol), K₂PO₄ (744 mg, 3.50 mmol), andDME (10 mL) were added. The mixture was stirred at 80° C. for 3 hours.The 3,5-bis(trifluoromethyl)biphenyl was obtained (68.2% yield) as acolorless oil. The identity of the 3,5-bis(trifluoromethyl)biphenyl wasconfirmed by comparison to the GC retention time and ¹H NMR data to anauthentic sample prepared from 3,5-bis(trifluoromethyl)phenylpinacolborane and iodobenzene. ¹H NMR (CDCl₃, 300 MHz) δ 8.00 (s, 2H),7.93 (s, 1H), 7.85−7.58 (m, 2H), 7.53−7.42 (m, 3H).

EXAMPLE 3

This example shows a closed system for a two-step, one-vessel processfor synthesis of a biphenyl from benzene, a borane (HBPin), and ahalogenated phenyl (PhI). An arylboronate ester was produced using an Ircatalyst and the arylboronate was subsequently coupled to thehalogenated phenyl using a palladium catalyst.

In a glove box, benzene (437 mg, 5.60 mmol), Ir(COD)(Indenyl) (3.0 mg,0.0070 mmol), dppe (2.8 mg, 0.0070 mmol), dodecane (internal standard,11.5 mg, 0.0675 mmol), and HBPin (45 mg, 0.352 mmol) were added to a J.Young tube equipped with a stir bar. The tube was then sealed, removedfrom the box, and heated at 100° C. for 18 hours. A GC trace of thereaction mixture revealed PhBPin in 85.7% yield.

Next, the reaction solution was allowed to cool to room temperature andPd(PPh₃)₄ (8.1 mg, 0.007 mmol), K₃PO₄ (112 mg, 0.528 mmol), PhI (72.7mg, 0.356 mmol) and DME (2 mL) were added. Three freeze-pump-thaw cycleswere performed to remove residual oxygen and the reaction mixture washeated at 80° C. for two days. GC analysis showed 81.8% GC-yield of thebiphenyl, 79.7% GC-conversion of the iodobenzene, and 79.1% conversionof the PhBPin.

EXAMPLE 4

This example shows an open system for a two-step, one-vessel process forsynthesis of a biphenyl from benzene, a borane (HBPin), and ahalogenated phenyl (PhI). An arylboronate ester was produced using an Ircatalyst and the arylboronate was subsequently coupled to thehalogenated phenyl using a palladium catalyst.

In a glove box, benzene (1.0 mL, 11.2 mmol), Ir(COD)(Indenyl) (3.0 mg,0.0070 mmol), dppe (2.8 mg, 0.0070 mmol), dodecane (internal standard,12.0 mg, 0.07 mmol), and HBPin (45 mg, 0.352 mmol) were added to aSchlenk tube equipped with a stir bar. The tube was then sealed, removedfrom the box, and heated at 100° C. for 18 hours with constant stirring.

Next, the reaction solution was allowed to cool to room temperature andPd(PPh₃)₄ (8.5 mg, 0.0074 mmol), K₃PO₄ (112 mg, 0.528 mmol), PhI (74.9mg, 0.367 mmol) and DME (2 mL) were added. A GC trace of the reactionmixture revealed PhBPin in 78.9% yield. The reaction mixture was thendegassed by purging with nitrogen and stirred at 90-95° C. for 16.5hours. A GC analysis showed a 97.3% yield of the biphenyl, 84.1%GC-conversion of the iodobenzene, and 90.7% conversion of the PhBPin.

EXAMPLE 5

This example shows an open system for a two-step, one-vessel process forsynthesis of a biaryl from 1,3-dichlorobenzene, a borane (HBPin), and a3-bromotoluene.

In a glove box, 1,3-dichlorobenzene, Ir(COD)(Indenyl) (2 mol %), dppe (2mol %), and HBPin were added to a Schlenk tube equipped with a stir bar.The tube was then sealed, removed from the box, and heated at 100° C.for 16 hours with constant stirring.

Next, the reaction solution was allowed to cool to room temperature andPd(PPh₃)₄ (2 mol %), K₃PO₄), 3-bromotoluene and DME (2 mL) were added.The reaction mixture was incubated at 80° C. for 17 hours. A CG analysisfollowing the reaction showed an 80% yield of the biaryl from the1,3-dichlorobenzene.

EXAMPLE 6

This example shows an open system for a two-step, one-vessel process forsynthesis of a hyperbranched polyphenylene from 1,3-dibromobenzene.

In a glove box, 1,3-dibromobenzene, Ir(COD)(Indenyl) (2 mol %), dppe (2mol %), and HBPin were added to a Schlenk tube equipped with a stir bar.The tube was then sealed, removed from the box, and heated at 100° C.for 16 hours with constant stirring.

Next, the reaction solution was allowed to cool to room temperature andPd₂(dba)₃ (0.5 mol %), K₃PO₄, 3-bromotoluene, and ^(t)Bu₃P, were added.The reaction mixture was incubated for 15 hours with refluxing xylenes.The hyperbranched polyphenylene was similar to that obtained by theprocess of Kim and Webster (Macromolec. 25: 5561-5572 (1992).

While the present invention is described herein with reference toillustrated embodiments, it should be understood that the invention isnot limited hereto. Those having ordinary skill in the art and access tothe teachings herein will recognize additional modifications andembodiments within the scope thereof. Therefore, the present inventionis limited only by the claims attached herein.

1. A process for producing a substitute aromatic compound in one vessel,which comprises: (a) reacting in a reaction mixture first aromaticorganic compound selected from the group consisting of an aryl, a sixmembered heteroaromatic compound, and a five membered heteroaromaticcompound with a borane selected from the group consisting of a boranewith a B—H, B—B, and B—Si bond in the presence of a catalyticallyeffective amount of an iridium or rhodium complex with three or moresubstituents, and an organic ligand selected from the group consistingof phosphorus, carbon, nitrogen, oxygen, and sulfur organic ligands toform an aromatic boron compound in the reaction mixture; and (b)reacting the aromatic boron compound in the reaction mixture with asecond aromatic organic compound selected from the group consisting ofhalide, triflate, and nonaflate in the presence of a catalyticallyeffective, amount of a metal catalyst and in the presence of the iridiumor rhodium, in the reaction mixture from step (a), wherein an aromaticgroup of the second aromatic organic compound is coupled to an aromaticgroup of the first aromatic organic boron compound to produce thesubstituted aromatic compound.
 2. The process of claim 1, wherein thethree or more substituents excludes hydrogen.
 3. The process of claim 1wherein the iridium complex with the ligand is selected from the groupconsisting of (Cp*)Ir(H)₂(Me₃P), (Cp*)Ir(H)(BPin)(Me₃P),(Cp*)Ir(H)(C₆H₅)(Me₃P), (Ind)Ir(COD), (Ind)Ir(dppe),(MesH)Ir(BPin)(B(OR)₂)₂, ((R₁)₃P)₃Ir(B(OR₂)₂)₃, (R₁)₂P)₂Ir(BPin)₃,(((R₁)₂P)₃Ir((R₂O)₂B)₃)₂, ((R₁)₃P)₄Ir(BPin), ((R₁)₃P)₂Ir(BPin)₃,(MesH)Ir(BPin)₃, and (IrCl(COD))₂, (PMe₃)₂IrH₅, ((R₁)₃P)₂IrH₅, and((R)₃P)₂IrH_(x)(B(OR₂)₂)_(5−x) where x is 0-4, wherein Cp* is1,2,3,4,5-methylcyclopentadienyl, BPin is pinacolborane, Me is methyl, His hydrogen, P is phosphorus, Ind is indenyl, COD is 1,5-cyclooctadiene,MesH is mesitylene, and wherein R, R₁, and R₂ are hydrogen, linear orbranched alkyl containing 1 to 8 carbons, aryl, or a carbon in a cyclicstructure.
 4. The process of claim 1 wherein the iridium complex is(Ind)Ir(COD) wherein Ind is indenyl and COD is 1,5-cyclooctadiene. 5.The process of claim 1 wherein the iridium complex with the ligand is(MesH)Ir(BPin)₃ wherein MesH is mesitylene and BPin is pinacolborane. 6.The process of claim 1 wherein the iridium complex is (IrCl(COD) )₂wherein COD is 1,5-cyclooctadiene.
 7. The process of claim 1 wherein therhodium complex with the ligand is selected from the group consisting of(Cp*)Rh(H)₂(Me₃P), (Cp*)Rh(H)(BPin)(Me₃P) (Cp*)Rh(H)(C₆H₅)(Me₃P), and(Cp*)Rh(hexamethylbenzene), wherein Cp* is1,2,3,4,5-methylcyclopentadienyl, BPin is pinacolborane, Me is methyl, His hydrogen, and P is phosphorus.
 8. The process of claim 1 or 2 whereinthe phosphorus organic ligand is selected from the group consisting oftrimethyl phosphine (PMe₃), 1,2-bis(dimethylphosphino)ethane (dmpe),Ph₃P, Cy₃P, and 1,2-bis(diphenylphosphino)ethane (dppe).
 9. The processof claim 1 wherein the borane is a borane ester.
 10. The process ofclaim 1, wherein the borane is pinacolborane.
 11. The process of claim 1wherein the metal is palladium.
 12. The process of claim 1 wherein themetal catalyst complex is selected from Pd(PPh₃)₄, Pd₂(dba)₃/P(^(t)Bu)₃,PdCl₂(dppf), and Pd(OAc)₂/Cy₃P wherein P is phosphorus and Ph is phenyl,dba is dibenzylideneacetone, ^(t)Bu is tert-butyl, dppf isdiphenylphosphinoferrocene.
 13. A process for producing an organicsubstituted aryl or heteroaryl compound, which comprises: (a) reactingin a reaction mixture in a reaction vessel a first aromatic organiccompound selected from the group consisting of an aryl, a six memberedheteroaromatic compound, and a five membered heteroaromatic compoundwith a borane selected from the group consisting of a borane with a B—H,B—B and B—Si bond in the presence of a catalytically effective amount ofan iridium or rhodium complex with three or more substituents, and anorganic ligand selected from the group consisting of phosphorus, carbon,nitrogen, oxygen, and sulfur organic ligands to form an aromatic boroncompound in the reaction mixture; and (b) reacting the aromatic boroncompound in the reaction mixture in the reaction vessel with a secondaromatic organic compound selected from the group consisting of halide,triflate, and nonaflate in the presence of a catalytically effectiveamount of a metal catalyst and in the presence of the iridum or rhodiumin the reaction mixture from step (a) wherein an aromatic group of thesecond aromatic organic compound is coupled to an aromatic group of thefirs aromatic organic boron compound to produce the organic substitutedaryl or heteroaryl compound.
 14. The process of claim 13 wherein thethree or more substituents excludes hydrogen.
 15. The process of claim13 wherein the iridium complex with the ligand is selected from thegroup consisting of (Cp*)Ir(H)₂(Me₃P), (Cp*)Ir(H)(BPin)(Me₃P),(Cp*)Ir(H)(C₆H₅)(Me₃P), (Ind)Ir(COD), (Ind)Ir(dppe),(MesH)Ir(BPin)(B(OR)₂), ((R₁)₃P)₃Ir(B(OR₂)₂)₃, (R₁)₃P)₂Ir(BPin)₃,(((R₁)₃P)₃Ir((R₂O)₂B)₃)₂, ((R₁)₃P)₄Ir(BPin), ((R₁)₂P)₃Ir(BPin)₃,(MesH)Ir(BPin)₃, (PMe₃)₂IrH₅, ((R₁)₃P)₂IrH₅, and((R₁)₃P)₂IrH_(x)(B(OR₂)₂)_(5−x), where x is 0-4, (IrCl(COD))₂, whereinCp* is 1,2,3,4,5-methylcyclopentadienyl, BPin is pinacolborane, Me ismethyl, H is hydrogen, P is phosphorus, Ind is indenyl, COD is1,5-cyclooctadiene, MesH is mesitylene, and wherein R, R₁, and R₂ arehydrogen, linear or branched alkyl containing 1 to 8 carbons, aryl, or acarbon in a cyclic structure.
 16. The process of claim 13 wherein theiridium complex is (Ind)Ir(COD) wherein Ind is indenyl and COD is1,5-cyclooctadiene.
 17. The process of claim 13 wherein the iridiumcomplex with the ligand is (MesH)Ir(BPin)₃ wherein MesH is mesityleneand BPin is pinacolborane.
 18. The process of claim 13 wherein theiridium complex is (IrCl(COD) )₂ wherein COD is 1,5-cyclooctadiene. 19.The process of claim 13 wherein the rhodium complex is selected from thegroup consisting of (Cp*)Rh(H)₂(Me₃P), (Cp*)Rh(H)(BPin)(Me₃P),(Cp*)Rh(H)(C₆H₅)(Me₃P), and (Cp*)Rh(hexamethylbezene), wherein Cp* is1,2,3,4,5-methylcyclopentadienyl, BPin is pinacolborane, Me is methyl, His hydrogen, and P is phosphorus.
 20. The process of claim 13 whereinthe phosphorus organic ligand is selected from the group consisting oftrimethyl phosphine (PMe₃), 1,2-bis(dimethylphosphino)ethane (dmpe),Ph₃P, Cy₃P, and 1,2-bis(diphenylphosphino)ethane (dppe).
 21. The processof claim 13 wherein the borane is a borane ester.
 22. The process ofclaim 13 wherein the borane is pinacolborane.
 23. The process of claim13 wherein the metal is palladium.
 24. The process of claim 13 whereinthe metal catalyst complex is selected from Pd(PPh₃)₄,Pd₂(dba)₃/P(^(t)Bu)₃, PdCl₂(dppf), and Pd(OAc)₂/PCy₃ wherein P isphosphorus and Ph is phenyl, dba is dibenzylideneacetone, ^(t)Bu istert-butyl, dppf is diphenylphosphinoferrocene.